Methods for the valorization of carbohydrates

ABSTRACT

There are provided methods for the valorization of carbohydrates. The methods comprise reacting a fluid comprising at least one carbohydrate with at least one metal catalyst or at least one metal catalytic system in a fluidized bed reactor so as to obtain at least one organic acid or a derivative thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 14/241,389(filed on Jun. 17, 2014), that is 35 USC 371 national stage entry ofPCT/CA2012/000781 (filed on Aug. 22, 2012) and that claims priority onU.S. 61/527,711 (filed on Aug. 26, 2011). These documents are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to improvements in the field of chemistryand chemical engineering applied to the preparation of organiccompounds. More particularly, it relates to methods for the valorizationof carbohydrates.

BACKGROUND OF THE DISCLOSURE

There are many paths to adding value to carbohydrates from the simplethermal treatments—combustion, gasification, pyrolysis, andliquefaction—to enzymatic processes. In the former, energy is the goalor simple molecules like hydrogen and CO that can be used to as afeedstock leading to methanol, olefins, methane, diesel, etc. In thelatter, the principal target molecules are alcohols—ethanol, butanol—forfuel. The major cost factors of the sugar-to-alcohol process includefeedstock, enzyme, and fermentation. Fermentation is an inherentlyinefficient process in which maximum carbon yields of better than 50%are difficult to achieve.

There is thus a need for providing alternative methods for thevalorization of carbohydrates. Moreover, there is a need for providingmethods that would overcome at least one of the drawbacks of the methodsfound in the prior art.

SUMMARY OF THE DISCLOSURE

According to one aspect, there is provided a method for the valorizationof carbohydrates, the method comprising:

-   -   reacting a fluid comprising at least one carbohydrate with at        least one metal catalyst or at least one metal catalytic system        in a fluidized bed reactor so as to obtain at least one organic        acid or a derivative thereof.

According to another aspect, there is provided a method for thevalorization of carbohydrates, the method comprises:

-   -   reacting a fluid comprising at least one carbohydrate with at        least one metal catalyst or at least one metal catalytic system        under conditions suitable for at least substantially preventing        caramelization of the at least one carbohydrate, so as to obtain        at least one organic acid or a derivative thereof.

It was found that the methods described in the present disclosure allowfor high throughput rates and high reaction rates. These methods arealso efficient for being carried out in smaller reaction vessels andprovide high selectivities.

It was also found that the methods of the present disclosure allow forlowering yield losses (for example versus fermentation, which is notmuch better than 50%) and for lowering the number of unit operations aswell as the number of steps required in the production process, therebylowering the production costs.

It was also found that by carrying out the reaction between the at leastone carbohydrate and the at least one metal catalyst in fluidized bedreactor, it was possible to avoid caramelization of the at least onecarbohydrate. In fact, it was observed that it was possible to avoidcaramelization problems, problems that render very difficult suchchemical processes for various reasons including difficult intermediatesand by-products to work with (caramelized products) and degradation ofthe carbohydrates. Without being bound or limited to such a theory,Applicants believe that by using a fluidized bed reactor, since the heattransfer is so rapid, the at least one carbohydrate will heat up andreact catalytically faster than the caramelization reaction.

It was thus observed that using a fluid bed reactor was efficient forproviding conditions suitable for at least substantially preventingcaramelization of the at least one carbohydrate.

It was also found that by providing reaction conditions at which thecaramelization of the at least one carbohydrate is slower than thereaction between the at least one carbohydrate and the at least onemetal catalyst that produces the at least one organic acid or aderivative thereof, it was possible to at least substantially preventcaramelization of the at least one carbohydrate.

It was also found that by carrying out the methods at a temperaturebelow a temperature at which caramelization of the at least onecarbohydrate is faster than the reaction between the at least onecarbohydrate and the at least one metal catalyst that produces the atleast one organic acid or a derivative thereof, it was possible to atleast substantially prevent caramelization of the at least onecarbohydrate.

Finally, it was also found that the methods of the present disclosureare effective for reacting sugars (for example pentoses) directly, thatis, based on the knowledge of the applicants, currently uncommon forfermentation processes. The person skilled in the art would clearlyunderstand that such methods could be applied to various othercarbohydrates for example, to various other carbohydrates as describedin the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the disclosure will become morereadily apparent from the following description of various embodimentsas illustrated by way of examples in the appended figures wherein:

FIG. 1 is a schematic representation of an example of a reactor that canbe used for carrying out the methods described in the presentdisclosure; and

FIG. 2 represents High Pressure Liquid Chromatography (HPLC) resultsobtained from a sample prepared in accordance with an example of amethod as described in the present disclosure.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Further features and advantages will become more readily apparent fromthe following description of various embodiments as illustrated by wayof examples only and in a non-limitative manner.

The expression “organic acid or a derivative thereof” as used hereinrefers to an organic acid or a derivative thereof. For example, thederivative of the organic acid can be an anhydride, a salt, an amide, anester, an acid halide etc.

The term “suitable” as used herein means that the selection of theparticular compound and/or conditions would depend on the specificmanipulation to be performed, but the selection would be well within theskill of a person trained in the art. All process/method describedherein are to be conducted under conditions sufficient to provide thedesired product (for example at least one organic acid or a derivativethereof). A person skilled in the art would understand that all reactionconditions, including, for example, reaction time, reaction temperature,reaction pressure, reactants concentration and/or ratio, injection rates(carbohydrate or a composition thereof and/or fluidization gas) andwhether or not the reaction should be performed under inert atmosphere,can be varied to optimize the yield of the desired product and it iswithin their skill to do so.

Terms of degree such as “about” and “approximately” as used herein meana reasonable amount of deviation of the modified term such that the endresult is not significantly changed. These terms of degree should beconstrued as including a deviation of at least ±5% or at least ±10% ofthe modified term if this deviation would not negate the meaning of theword it modifies.

For example, the method can comprise injecting atomized droplets of acarbohydrate-containing composition that comprises the at least onecarbohydrate and water into the fluidized bed reactor.

For example, the atomized droplets can be vaporized in situ wheninserted into the fluidized bed reactor.

For example, the fluid can be a gas, a liquid or a mixture thereof.According to one embodiment, the fluid can be synthetic air. Accordingto another embodiment, the fluid can be air having a concentration of O₂of about 0 to about 21%.

The carbohydrate can be at a concentration of about 1 wt % to about 20wt %, about 2 wt % to about 18 wt %, about 5 wt % to about 15 wt %,about 10 wt % to about 15 wt %, about 8 wt % to about 12 wt %, or about10 wt %, based on the total weight of the carbohydrate-containingcomposition.

For example, the composition can be injected at a rate of about 0.5mL/minute to about 10 mL/minute, about 1 mL/minute to about 8 mL/minute,about 2 mL/minute to about 6 mL/minute or about 3 mL/minute to about 5mL/minute per about 0.2 L of capacity of the fluidized bed reactor.

For example, the fluidization gas can be injected at a flow rate ofabout 100 mL to about 20000 mL/minute, 400 mL/minute to about 2000mL/minute, about 500 mL/minute to about 1500 mL/minute, about 600mL/minute to about 1200 mL/minute, or about 800 mL/minute to about 1000mL/minute per 0.2 L of capacity of the fluidized bed reactor.

For example, the at least one metal catalyst or the at least one metalcatalytic system can be an oxidation catalyst.

Examples of oxidation catalysts can comprise vanadium pyrophosphate,iron phosphate, VPO catalyst, V₂O₅ or mixtures thereof.

Examples of oxidation catalysts can comprise VOPO₄ (for example α-VOPO₄or γ-VOPO₄) VOHPO₄, (VO)₂P₂O₇, VO(PO₃)₂, VO(H₂ PO₄)₂ or mixturesthereof.

Examples of oxidation catalysts can be chosen from vanadium phosphorusoxide catalysts.

Other examples of metal catalysts or metal catalytic systems can includeany or a combination of Au, Pt, Rh, Ru, Pd, Cu, Ni or Fe or generallythe transition metals supported over alumina, silica or zeolites as wellas Mo, Re, Fe, Pd, Cu or Pt supported over HZSM-5 or Rh supported overNaY zeolites. Specific examples include supported or bulk Sn basedcatalysts such as SnCl₂ or Cu/SiO₂, Cu/Al₂O₃, Cu/CeO₂, CuMnO₂, Cu/CuO,Cu/CuO/Al₂O₃, Cu/ZnO/Al₂O₃, Cu/ZnO/Cr₂O₃, Cu—Zn—Zr—Al—O systems as wellas MgAl₂O₄, Ag/TiO₂, V₂O₅/TiO₂, Pt/TiO₂, Pt/Al₂O₃, Pt/CeZr oxides,Pt/Cu/MnO₂, Pd/SiO₂, Pd/WO₃/ZrO₂, ZrO₂, ZnO₂/FeO/Al₂O₃. Other examplesinclude HSA alumina, Raney Cu on Pyrex, Cu flakes/chips, Cu over HSAsilica and Cu over colloidal silica. Raney Ni can be used forhydrogenation pathways while Rh and Pt are also capable of facilitatingthe hydrolysis reactions. Further examples include supported ornon-supported catalytic systems of the type ABCD-O, ABCD-P—O or ABCD,where A, B, C and D may represent any or a combination of Mo, V, Te, Ta,Si, Sb or Nb.

For example, the at least one carbohydrate can be a hexose, a pentose,or a mixture thereof.

For example, the at least one carbohydrate can be chosen from xylose,arabinose, lyxose, ribose, ribulose, xylulose, allose, altrose, glucose,mannose, gulose, idose, galactose, talose, and mixtures thereof.

For example, the at least one carbohydrate can be chosen from the familyof aldopentoses, ketopentoses, aldohexoses, and/or ketohexoses,including their hemiacetals and hemiketals ring structures.

The at least one carbohydrate can be reacted with the metal catalyst ata temperature of about 240° C. to about 360° C., about 260° C. to about320° C., about 275° C. to about 325° C., about 290° C. to about 310° C.,or about 280° C. to about 300° C.

For example, the at least one organic acid can be chosen from acrylicacid, methacrylic acid, maleic acid, fumaric acid, acetic acid, andmixtures thereof.

For example, the methods can be carried out under conditions suitablefor at least substantially preventing caramelization of the at least onecarbohydrate. For example, the conditions suitable for at leastsubstantially preventing caramelization of the at least one carbohydratecan comprise conditions at which caramelization of the at least onecarbohydrate is slower than the reaction between the at least onecarbohydrate and the at least one metal catalyst that produces the atleast one organic acid or a derivative thereof. For example, theconditions suitable for at least substantially preventing caramelizationof the at least one carbohydrate can comprise carrying out the reactionout at a temperature below a temperature at which caramelization of theat least one carbohydrate is faster than the reaction between the atleast one carbohydrate and the at least one metal catalyst that producesthe at least one organic acid or a derivative thereof.

Experiments of catalytic sugar oxidation process in a fluidized bed athigh temperature have been carried out for the valorization ofcarbohydrates. Such experiments have been carried out using a fluidizedbed as shown in FIG. 1. A aqueous solution of 10 wt % of xylose wasinjected to the fluidized catalyst bed at a rate of 0.5 mL/min via ametering pump. The fluidization gas was synthetic air (21% oxygen inargon) and the gas flow rate was 800-1000 ml/min and was controlled by aflow meter. About 200 g of a calcined VPO catalyst were used and thereaction temperature was about 300° C. and maintained by the heatingelements (connected to thermocouple). The reactor temperature was stablethroughout the reaction and no crystallization or deposition of sugarinside the bed was observed. In the conditions described above, about 24g of solution were collected after 1 hour of reaction. It was analyzedby HPLC and GC (Gas Chromatography). The gas portion was analyzed by MS(Mass Spectrometry). FIG. 2, demonstrates a graphical view of the HPLCanalysis results performed on the liquid produced from the reaction at300° C. The HPLC analysis showed a range of organic acids and some otheracid products. The major produced acids were maleic acid and acrylicacid. Moreover, methacrylic acid and fumaric acid were also observed.

The person skilled in the art would understand that, when applicable,all the various embodiments presented in the present disclosure can beused in combination with all the methods described in the “SUMMARY OFTHE DISCLOSURE” section. Moreover, the person skilled in the art wouldunderstand that, when applicable, all the various embodiments presentedin the present disclosure can be used in combination with any otherembodiments presented in the present disclosure and/or in the “SUMMARYOF THE DISCLOSURE” section.

While a description was made with particular reference to the specificembodiments, it will be understood that numerous modifications theretowill appear to those skilled in the art. Accordingly, the abovedescription and accompanying drawings should be taken as specificexamples and not in a limiting sense.

What is claimed is:
 1. A method for the valorization of carbohydrates,said method comprising: reacting a fluid comprising at least onecarbohydrate with at least one oxidation metal catalyst or at least oneoxidation metal catalytic system in a fluidized bed reactor so as toobtain at least one organic acid or an anhydride thereof, a saltthereof, an amide thereof, an ester thereof or an acid halide, said atleast one oxidation metal catalyst or said at least one oxidation metalcatalytic system comprising at least one metal chosen from V, Au, Cr,Mg, Ag, Pt, Rh, Sn, Al, Ce, Ru, Mo, Re, Pd, Te, Ta, Si, Sb, Nb, Cu, Zr,Ti, Mn, Zn, W, Ni and Fe.
 2. The method of claim 1, wherein said methodcomprises injecting atomized droplets of a carbohydrate-containingcomposition that comprises said at least one carbohydrate and water intosaid fluidized bed reactor.
 3. The method of claim 2, wherein saidatomized droplets are vaporized in situ when inserted into saidfluidized bed reactor.
 4. The method of claim 3, wherein saidcarbohydrate is at a concentration of about 1 wt % to about 20 wt %,based on the total weight of the carbohydrate-containing composition. 5.The method of claim 2, wherein said carbohydrate is at a concentrationof about 5 wt % to about 15 wt %, based on the total weight of thecarbohydrate-containing composition.
 6. The method of claim 5, whereinsaid composition is injected at a rate of about 0.5 mL/minute to about10 mL/minute per about 0.2 L of capacity of said fluidized bed reactor.7. The method of claim 1, wherein said method involves the use of saidat least one oxidation metal catalyst that is chosen from vanadiumpyrophosphate, iron phosphate, V₂O₅, and mixtures thereof.
 8. The methodof claim 1, wherein said at least one metal catalyst or said at leastone metal catalytic system includes any or a combination of Au, Pt, Rh,Ru, Pd, Cu, Ni or Fe or generally the transition metals supported overalumina, silica or zeolites as well as Mo, Re, Fe, Pd, Cu or Ptsupported over HZSM-5 or Rh supported over NaY zeolites, for examplesinclude supported or bulk Sn based catalysts.
 9. The method of claim 1,wherein said at least one metal catalyst or said at least one metalcatalytic system is chosen from SnCl₂ Cu/SiO₂, Cu/Al₂O₃, Cu/CeO₂,CuMnO₂, Cu/CuO, Cu/CuO/Al₂O₃, Cu/ZnO/Al₂O₃, Cu/ZnO/Cr₂O₃, Cu—Zn—Zr—Al—OMgAl₂O₄, Ag/TiO₂, V₂O₅/TiO₂, Pt/TiO₂, Pt/Al₂O₃, Pt/CeZr oxides,Pt/Cu/MnO₂, Pd/SiO₂, Pd/WO₃/ZrO₂, ZrO₂, ZnO₂/FeO/Al₂O₃, and mixturesthereof.
 10. The method of claim 1, wherein said at least one metalcatalytic system is HSA alumina, Raney Cu on Pyrex, Cu flakes/chips, Cuover HSA silica or Cu over colloidal silica.
 11. The method of claim 1,wherein said at least one metal catalytic system is chosen fromsupported or non-supported catalytic systems of the type ABCD-O,ABCD-P—O or ABCD, where A, B, C and D each independently Mo, V, Te, Ta,Si, Sb or Nb.
 12. The method of claim 1, wherein said at least one metalcatalyst comprises a VPO catalyst.
 13. The method of claim 1, whereinsaid at least one metal catalyst comprises VOPO₄, VOHPO₄, (VO)₂P₂O₇,VO(PO₃)₂, VO(H₂ PO₄)₂ or mixtures thereof.
 14. The method of claim 1,wherein said method comprises obtaining at least one organic acid. 15.The method of claim 1, wherein said method comprises obtaining at leastone organic acid anhydride.
 16. The method of claim 1, wherein saidmethod comprises obtaining at least one maleic acid anhydride.
 17. Amethod for the valorization of carbohydrates, said method comprising:reacting a fluid comprising at least one carbohydrate with at least oneoxidation metal catalyst or at least one oxidation metal catalyticsystem in a fluidized bed reactor so as to obtain at least one organicacid or an anhydride thereof, a salt thereof, an amide thereof, an esterthereof or an acid halide, said at least one oxidation metal catalyst orsaid at least one oxidation metal catalytic system comprising: any or acombination of Au, Pt, Rh, Ru, Pd, Cu, Ni or Fe or generally thetransition metals supported over alumina, silica or zeolites as well asMo, Re, Fe, Pd, Cu or Pt supported over HZSM-5 or Rh supported over NaYzeolites, for examples include supported or bulk Sn based catalysts; atleast one metal catalytic system chosen from SnCl₂ Cu/SiO₂, Cu/Al₂O₃,Cu/CeO₂, CuMnO₂, Cu/CuO, Cu/CuO/Al₂O₃, Cu/ZnO/Al₂O₃, Cu/ZnO/Cr₂O₃,Cu—Zn—Zr—Al—O MgAl₂O₄, Ag/TiO₂, V₂O₅/TiO₂, Pt/TiO₂, Pt/Al₂O₃, Pt/CeZroxides, Pt/Cu/MnO₂, Pd/SiO₂, Pd/WO₃/ZrO₂, ZrO₂, ZnO₂/FeO/Al₂O₃, andmixtures thereof; at least one metal catalytic system that is HSAalumina, Raney Cu on Pyrex, Cu flakes/chips, Cu over HSA silica or Cuover colloidal silica; at least one metal catalytic system chosen fromsupported or non-supported catalytic systems of the type ABCD-O,ABCD-P—O or ABCD, where A, B, C and D each independently Mo, V, Te, Ta,Si, Sb or Nb; at least one metal catalyst comprises a VPO catalyst; orat least one metal catalyst comprises VOPO₄, VOHPO₄, (VO)₂P₂O₇,VO(PO₃)₂, VO(H₂PO₄)₂ or mixtures thereof.
 18. The method of claim 17,wherein said method comprises obtaining at least one organic acidanhydride.
 19. The method of claim 17, wherein said method comprisesobtaining at least one maleic acid anhydride.
 20. A method for thevalorization of carbohydrates, said method comprising: reacting a fluidcomprising at least one carbohydrate with at least one oxidation metalcatalyst or at least one oxidation metal catalytic system in a fluidizedbed reactor so as to obtain at least one organic acid or an anhydridethereof, a salt thereof, an amide thereof, an ester thereof or an acidhalide.